Filter device

ABSTRACT

A filter device, having a filter housing ( 1 ) which has a filter head ( 3 ), a filter pot ( 7 ) and a removable housing cover part ( 51 ) and which accommodates a filter element ( 13 ) which separates a non-filtrate side ( 15 ) from a filtrate side ( 17 ), and having a bypass valve device which has a valve closure element ( 65 ) which is preloaded by means of a closing spring ( 69 ) into a closed position in which it bears against a valve seat part ( 74 ) and which, if the filter element ( 13 ) is blocked, passes into a position in which it opens up a fluid path from the non-filtrate side ( 15 ) to the filtrate side ( 17 ), by passing the filter element ( 13 ), is distinguished by the fact that the valve closure element ( 65 ) and the closing spring ( 69 ) are arranged on the cover part ( 51 ) and the valve seat part ( 74 ) is situated on an element cap ( 43 ) of the filter element ( 13 ), which element cap has a receiving part ( 45 ) which forms an enclosure for that end of the filter material ( 27 ) of the filter element ( 13 ) which faces toward the cover part ( 51 ).

The invention relates to a filter device, having a filter housing which has a filter head, a filter bowl and a removable housing cover part and which accommodates a filter element, which separates a non-filtrate side from a filtrate side, and having a bypass valve device which has a valve closure element which is preloaded by means of a closing spring into a closed position in which it bears against a valve seat part and which, in the case of a blocked filter element, passes into a position in which it opens up a fluid path from the non-filtrate side to the filtrate side, bypassing the filter element.

Filter devices of this kind are state of the art and can be easily commercially obtained in a variety of designs. To cite just one example from the large number of known devices of this kind, reference is made to document EP 2 249 941B1 for example. When filter devices of this kind are used in technical equipment, such as hydraulic systems, the operational reliability of the associated equipment is largely dependent on the functional capability of the filter device. To prevent significant operational disruption from occurring in the case of a blockage of the filter element, during which the filter material thereof is overloaded with dirt particles cleaned from the fluid, the bypass valve device forms a kind of safety device which provides, as an emergency measure, a fluid path which bypasses the blocked filter material. Given the large quantities in which such filter devices are used, the production costs for such filter devices constitute a significant economic factor.

In view of these issues, the problem addressed by the invention is to provide a filter device of the type specified above, which is distinguished by a simple design which can be particularly cost-effectively produced.

According to the invention, this problem is solved by means of a filter device having the features of claim 1 in its entirety.

According to the characterizing part of claim 1, a significant distinguishing feature of the invention is that the valve closure element and the closing spring are arranged on the cover part and the valve seat part is located on an element cap of the filter element, which element cap has a receiving part forming an enclosure for the end of the filter element facing the cover part. The formation of the valve seat part on an element cap of the filter element allows the bypass valve device to be realized in a simple manner and with little material expenditure. Because the formation of the bypass valve device accounts for a not insignificant proportion of the production costs of such filter devices, the overall filter device can be correspondingly cost-effectively produced.

In particularly advantageous exemplary embodiments, the valve closure element is formed by a hollow cylinder, the cavity of which is closed at one end by means of a base, on which the one end of a compression spring located in the cavity is supported, with the other end thereof being supported on the cover part.

The arrangement can particularly advantageously be such that, in order to form a kind of valve housing for the bypass valve device, a circular cylindrical guide wall is provided on the cover part projecting in the direction of the filter element, along which guide wall the hollow cylinder is guided with its external wall.

The arrangement can also advantageously be such that the hollow cylinder has a circumferential contact bevel on the outside on the end closed by the base, which circumferential contact bevel forms a valve cone which, during normal filtering operation, is held under the influence of the compression spring in tight contact with the valve seat part on the element cap.

In particularly advantageous exemplary embodiments, the element cap of the filter element has, on the enclosure for the facing end of the filter material, a receiving part in the form of a planar circular ring, to the internal circumference of which a guide part is connected which extends axially into the inner side of the filter element that forms the non-filtrate side, on which guide part the valve seat part is formed.

The guide part can advantageously have the form of a hollow cone, which extends with its tapered end having an opening into the inner side of the filter element and which forms at the edge of its opening the sealing edge of the valve cone. When the bypass valve opens, the fluid path thus extends through the hollow cone to the top side of the receiving part and beyond same to the outer side of the filter material which forms the filtrate side.

For the purpose of structural reinforcement, the hollow cone can have a ring of projecting guide brackets at the internal circumference.

In particularly advantageous exemplary embodiments, an additional ring of uniformly distributed brackets surrounds the external circumference of the annular receiving part of the element cap, which brackets, as a continuation of the brackets located in the hollow cone, are formed plate-like and extend with their planes in the radial direction and form the supports for an annular receiving crown, which is located at an axial distance from the receiving part and at a radial distance from the outer side of the remainder of the filter element.

The thus-formed receiving crown can be surrounded at its external circumference by a molded seal, which has a U-shaped profile cross-section, the one profile limb of which forms the seal relative to the cover part and the profile crosspiece and other profile limb of which form the seal between the receiving crown and the filter head. In a particularly advantageous manner, an overall seal between the non-filtrate side and the filtrate side is thus formed by means of a single sealing arrangement in conjunction with the bypass valve, which normally closes the opening of the element cap leading into the inner side of the filter element.

The receiving part, the brackets, the receiving crown and the guide part can, advantageously integrally connected to one another, form the element cap.

As an additional safety device, in addition to the bypass valve device, a differential pressure measurement device can be provided, which is preferably supplemented with an optical evaluation unit and signals the operational state of the filter material on the basis of the pressure gradient formed at the filter material.

The invention is explained in detail below with reference to an exemplary embodiment depicted in the drawings, in which:

FIG. 1 shows, in a schematically simplified perspective oblique view and cut open and truncated in the longitudinal direction, an exemplary embodiment of the filter device according to the invention and

FIG. 2 shows, on an enlarged scale compared with FIG. 1, broken off in the longitudinal direction and rotated by 90° relative to FIG. 1, a longitudinal section of the end region of the exemplary embodiment which has the filter head.

With reference to the attached drawings, the invention is explained using the example of a so-called in-tank filter device, in which the filter housing 1 has a filter head 3, on which flange parts 5 are located at the outside. The filter housing 1 can be mounted by these means on the edge of a top wall opening of a storage container or tank (not depicted) in such a way that a filter bowl 7, which is connected to the bottom end of the filter head 3, extends in the vertical direction into the inside of the tank. The length of the filter bowl 7 depicted truncated in FIGS. 1 and 2 is such that the bottom end 9 of the filter bowl 7 is located below the lowest level of fluid, e.g. hydraulic oil, to be expected during operation. In the design as an in-tank filter device, in the depicted example the filter bowl 7 in the form of a relatively thin-walled circular cylinder is fixed on the filter head 3 by means of a flanging 11. It shall be understood that the invention can be advantageously used not only in in-tank filter devices, but also in filter devices of other types.

For the filtering operation, in which a filter element 13 that can be accommodated in an exchangeable manner in the housing 1 can be flowed through from its inner side 15 which forms the non-filtrate side to its outer side 17 which forms the filtrate side, an inflow housing 19 is located at the bottom end 9 of the filter bowl 7, which at its top opening 21 leading to the inner side 15 of the filter element 13 forms a radially outwards projecting base 23, the peripheral edge 25 of which engages in the bottom end 9 of the filter bowl 7 and is crimped. The filter element 13 has an end cap 29 at the bottom end of its hollow cylindrical filter material 27, which end cap engages with an end ring body 31 in the opening 21 of the inflow housing 19. A flap valve 33, which is arranged at the central passage 35 of the end cap 29, opens for the flow of the fluid, which flows from the inlet connection 27 of the inflow housing 19 to the inner side 15 of the filter element 13.

In the filtering process, which occurs from the inside outwards through the filter material 27, said filter material 27 is supported against the flow forces by means of an external sheath 39, which has a perforation, for example in the form of a punched hole, and which forms a kind of external support tube. Instead of a sheath with punched holes, a grid structure or the like could also be provided. For the purpose of the outlet of the filtrate from the outer side 17 to the tank interior, window openings 41 are formed in the filter bowl 7. In accordance with the prior art which is standard in in-tank filters, the window openings 41 are not arranged over the entire length of the filter bowl 7, but instead only in selected surface areas. For example, the window openings 41 can, in accordance with the teaching provided in this respect by document EP 2 249 941 B1 and with adaption to the operational fluid level of the tank, be arranged in such a way that any gas bubbles located in the cleaned fluid can be separated and/or can be collected for a discharge.

As can be seen most clearly from FIG. 2, the filter element 13 has at its top side, which faces a housing cover part 51, which can be mounted in a removable manner on the filter head 3 by means of screws 53, a specially formed element cap 43, which is injection molded from a plastic material. However, it is also possible to form the element cap 43 from sheet metal or as an aluminum die cast part. As the central component, the element cap 43 has a receiving part 45 in the form of a planar circular ring which, as is standard in filter element end caps, forms an enclosure for the facing end of the filter material 27. A ring of uniformly distributed, plate-like brackets 47 surrounds the external circumference of the receiving part 45, the planes of which brackets extend in the radial direction and with said brackets forming the supports for an annular receiving crown 49, which is located at an axial distance from the receiving part 45 and at a radial distance from the outer side of the remainder of the filter element 13. A guide part 52 is connected to the bottom side of the receiving part 45 at the internal circumference thereof, which guide part has the form of a hollow cone, which extends axially with its tapered end 54 into the inner side 15 of the filter element 13 and ends at the bottom edge in a rib 55 projecting radially inwards. The brackets 47 continue below the receiving part 45 along the inner side of the guide part 52 as an additional ring of the brackets 47, which project radially inwards and extend from the bottom side of the receiving part 45 as far as the rib 55 at the bottom end 54 of the guide part 52.

As is shown most clearly in FIG. 2, the circumferential edge of the receiving crown 49 is enclosed by a molded seal 57, which has a U-shaped cross section and which with its top profile limb 59 forms the seal with the cover part 51, while the bottom profile limb 61 and the profile crosspiece 64 extending between the limbs 59 and 61 form the seal relative to the filter bowl 7. The molded seal 57 thus forms the seal of the overall fluid system situated above the tank wall relative to the environment.

A guide wall 63 is located on the bottom side of the cover part 51, which guide wall, in the form of a circular cylinder, projects coaxially into the inside of the hollow cone formed by the guide part 52 of the element cap 43. The guide wall 63 forms a kind of valve housing, in which the valve closure element of the bypass valve device is guided in a displaceable manner. This valve closure element is formed by a hollow cylinder 65, the cavity of which is closed at one end by means of a base 67, on which a compression spring 69 arranged in the cavity is supported, with the other end thereof being centered on a pin 71, which projects axially from the cover part 51. The hollow cylinder 65 forming the valve closure element, which is preloaded by means of the compression spring 69 into the closed position depicted in FIG. 2, forms at the end closed by means of the base 67 at the outside a circumferential contact bevel, which forms a valve cone 73 which, during normal filtering operation, is in sealing contact with the valve seat part under the influence of the compression spring 69, which valve seat part is formed by a sealing edge 74 at the inner edge of the rib 55 of the guide part 52. In the case of blockage of the filter material 27 of the filter element 13 and a corresponding pressure increase in the inner side 15 which forms the non-filtrate side and the thus-effected lifting of the valve cone 73, a bypass fluid path is formed inside the guide part 52 along the brackets 47 to the top side of the receiving part 45 and thus beyond the receiving part 45 to the outer side of the filtrate side, which is located on the outer side 17 of the filter material 27.

The element cap 43, which is formed in an integral manner together with the receiving part 45, the brackets 47, the receiving crown 49 and the guide part 52, is completed with a holding bracket 75, which is fixed in a foldable manner at the ring of brackets 47 and which facilitates the manipulation of the filter element 13 during installation and disassembly. In addition, a differential pressure measurement device 77 is provided which provides an indication of the operational state of the filter element 13 on the basis of the pressure gradient formed at the filter material 27 during filtering operation. The measurement device 77 has a measurement housing 79, which is screwed in a connection region 81 into the wall of the filter head 3. A spring-loaded measurement piston 82 is located in the measurement housing 79, the one end face of which piston is pressurized by the instantaneous pressure of the non-filtrate side and the other end face of which is pressurized by the instantaneous pressure of the filtrate side. For the supply of the instantaneous pressure of the filtrate side, the measurement housing 79 has a passage 83 on the end abutting the outer side (filtrate side). The pressure of the non-filtrate side passes from the inner side 15 via a channel run to the measurement housing 79, which channel run has a vertical channel section 84 at the element cap 43, which vertical channel section extends along a bracket 47, and has a horizontal channel section 85, which leads to a space 89 formed between the cover part 51 and the filter head 3, from where it passes via a wall opening into the measurement housing 79. In order to obtain an indication of the piston position of the measurement piston 82 which corresponds to the differential pressure, an evaluation unit 87 is connected to the outer end 15 of the measurement housing 79, which provides an optical signaling for example.

The receiving crown 49 is designed, up to the rib 55 that forms a sealing edge, as one part, which is preferably a component of the filter element as a whole. Because said part 49 is designed up to the sealing edge 55 as a cohesive component, despite the manufacturing tolerances which may apply to the filter element itself or to other components, the same opening pressure is always generated at the bypass valve, which represents a significant advantage compared with other solutions. Otherwise, the receiving housing for the bypass valve can also be designed in multiple parts up to the above-mentioned region. 

1. A filter device, having a filter housing (1) which has a filter head (3), a filter bowl (7) and a removable housing cover part (51) and which accommodates a filter element (13), which separates a non-filtrate side (15) from a filtrate side (17), and having a bypass valve device which has a valve closure element (65) which is preloaded by means of a closing spring (69) into a closed position in which it bears against a valve seat part (74) and which, in the case of a blocked filter element (13), passes into a position in which it opens up a fluid path from the non-filtrate side (15) to the filtrate side (17), bypassing the filter element (13), characterized in that the valve closure element (65) and the closing spring (69) are arranged on the cover part (51) and the valve seat part (74) is located on an element cap (43) of the filter element (13), which element cap has a receiving part (45) forming an enclosure for the end of the filter material (27) of the filter element (13) facing the cover part (51).
 2. The filter device according to claim 1, characterized in that the valve closure element is formed by a hollow cylinder (65), the cavity of which is closed at one end by means of a base (67), on which the one end of a compression spring (69) located in the cavity is supported, with the other end thereof being supported on the cover part (51).
 3. The filter device according to claim 1, characterized in that the cover part (51) has a circular cylindrical guide wall (63) projecting in the direction of the filter element (13), along which guide wall the hollow cylinder (65) is guided with its external wall.
 4. The filter device according to claim 1, characterized in that the hollow cylinder (65) has a circumferential contact bevel on the outside on the end closed by the base (67), which circumferential contact bevel forms a valve cone (73) which, during normal filtering operation, is held under the influence of the compression spring (69) in tight contact with the valve seat part (74) on the element cap (43).
 5. The filter device according to claim 1, characterized in that the element cap (43) of the filter element (13) has, at the enclosure for the facing end of the filter material (27), a receiving part (45) in the form of a planar circular ring, to the internal circumference of which a guide part (52) is connected which extends axially into the inner side (15) of the filter element (13) which forms the non-filtrate side, on which guide part the valve seat part (74) is formed.
 6. The filter device according to claim 1, characterized in that the guide part has the form of a hollow cone (52), which extends with its tapered end (54) having an opening into the inner side (15) of the filter element (13) and which at the edge (55) of its opening forms the sealing edge (74) of the valve closure element.
 7. The filter device according to claim 1, characterized in that the hollow cone (65) has a ring of projecting guide brackets (47) at the inner circumference.
 8. The filter device according to claim 1, characterized in that an additional ring of uniformly distributed, plate-like brackets (47) surrounds the external circumference of the annular receiving part (45) of the element cap (43), which brackets, as a continuation of the brackets (47) located in the hollow cone (65), are formed plate-like and extend with their planes in the radial direction and form the supports for an annular receiving crown (49), which is located at an axial distance from the receiving part (45) and at a radial distance from the outer side of the remainder of the filter element (13).
 9. The filter device according to claim 1, characterized in that the receiving crown (49) is surrounded at its external circumference by a molded seal (57), which has a U-shaped profile cross-section, the one profile limb (59) of which forms the seal relative to the cover part (51) and the profile crosspiece (64) and other profile limb (61) of which form the seal between the receiving crown (49) and the filter head (3).
 10. The filter device according to claim 1, characterized in that the receiving part (45), the brackets (47), the receiving crown (49) and the guide part (52), integrally connected to one another, form the element cap (43).
 11. The filter device according to claim 1, characterized in that a differential pressure measurement device (77) is provided, which is preferably supplemented with an optical evaluation unit (87). 